N-terminal pro-B-type natriuretic peptide and D-dimer combined with left atrial diameter to predict the risk of ischemic stroke in nonvalvular atrial fibrillation.

OBJECTIVES: We aimed to explore the potential role of N-terminal pro-B-type natriuretic peptide (NT-proBNP), d-dimer, and the echocardiographic parameter left atrial diameter (LAD) in identifying and predicting the occurrence of ischemic stroke (IS) in patients with nonvalvular atrial fibrillation (NVAF). METHODS: We conducted a retrospective study of 445 patients with NVAF in the First Affiliated Hospital of Nanchang University. They were divided into the NVAF (309 cases) and NVAF with stroke (136 cases) groups according to whether acute ischemic stroke (AIS) occurred at admission. Multivariate logistic regression was used to analyze the odds ratio (OR) of NT-proBNP, d-dimer, and LAD for IS. The predictive value of NT-proBNP, d-dimer, and LAD in identifying the occurrence of IS in NVAF was determined by plotting the receiver operating characteristic (ROC) curves. RESULTS: NT-proBNP, d-dimer, and LAD levels were significantly higher in the NVAF with stroke group than in the NVAF group (p < .05). NT-ProBNP, d-dimer, and LAD were independently associated with IS in NVAF patients (odds ratio [OR] = 1.12, 95% confidence interval [CI]: 1.08-1.16; OR = 1.87, 95% CI: 1.37-2.55; OR = 1.21, 95% CI: 1.13-1.28, p < .01). The optimal cutoff points for NT-ProBNP, d-dimer, and LAD levels to distinguish the NVAF group from the NVAF with stroke group were 715.0 pg/ml, 0.515 ng/ml, and 38.5 mm, respectively, with the area under the curve (AUC) being [0.801 (95% CI: 0.76-0.84); 0.770 (95% CI: 0.72-0.85); 0.752 (95% CI: 0.71-0.80), p < .01]. The combined score of NT-proBNP, d-dimer, and LAD improved the predictive efficacy of the single index, with an AUC of 0.846 (95% CI: 0.81-0.88, p < .01), sensitivity of 77.2%, and specificity of 76.4%. CONCLUSION: NT-proBNP, d-dimer, and the echocardiographic parameter LAD have outstanding value in predicting the risk of IS in patients with NVAF.

Visible Light-Mediated, Diastereoselective Epimerization of Morpholines and Piperazines to More Stable Isomers.

We report a photocatalyzed epimerization of morpholines and piperazines that proceeds by reversible hydrogen atom transfer (HAT) and provides an efficient strategy for editing the stereochemical configurations of these saturated nitrogen heterocycles, which are prevalent in drugs. The more stable morpholine and piperazine isomers are obtained from the more synthetically accessible but less stable stereoisomers, and a broad scope is demonstrated in terms of substitution patterns and functional group compatibility. The observed distributions of diastereomers correlate well with the relative energies of the diastereomer pairs as determined by density functional theory (DFT) calculations. Mechanistic studies, including luminescence quenching, deuterium labeling reactions, and determination of reversibility support a thiyl radical mediated HAT pathway for the epimerization of morpholines. Investigation of piperazine epimerization established that the mechanism is more complex and led to the development of thiol free conditions for the highly stereoselective epimerization of N,N'-dialkyl piperazines for which a previously unrecognized radical chain HAT mechanism is proposed.

General Light-Mediated, Highly Diastereoselective Piperidine Epimerization: From Most Accessible to Most Stable Stereoisomer.

We report a combined photocatalytic and hydrogen atom transfer (HAT) approach for the light-mediated epimerization of readily accessible piperidines to provide the more stable diastereomer with high selectivity. The generality of the transformation was explored for a large variety of di- to tetrasubstituted piperidines with aryl, alkyl, and carboxylic acid derivatives at multiple different sites. Piperidines without substitution on nitrogen as well as N-alkyl and aryl derivatives were effective epimerization substrates. The observed diastereoselectivities correlate with the calculated relative stabilities of the isomers. Demonstration of reaction reversibility, luminescence quenching, deuterium labeling studies, and quantum yield measurements provide information about the mechanism.

Cobalt(III)-Catalyzed Diastereoselective Three-Component C-H Bond Addition to Butadiene and Activated Ketones.

A highly diastereoselective three-component C-H bond addition across butadiene and activated ketones is described. This transformation provides homoallylic tertiary alcohols through the formation of two C-C σ bonds and with complete selectivity for an E-alkene isomer. The reaction exhibits good scope with respect to activated ketone inputs, including highly strained cyclic and electron-deficient cyclic and acyclic ketones. Additionally, high diastereoselectivities were achieved for alcohols prepared from unsymmetrical ketones.

Synthesis of Homoallylic Alcohols with Acyclic Quaternary Centers through CoIII -Catalyzed Three-Component C-H Bond Addition to Internally Substituted Dienes and Carbonyls.

An efficient CoIII -catalyzed three-component strategy to prepare homoallylic alcohols containing acyclic quaternary centers is disclosed. This transformation enables the introduction of two C-C σ bonds through C-H bond activation and sequential addition to internally substituted dienes and a wide range of aldehydes and activated ketones. Isoprene and other internally monosubstituted dienes are effective inputs, with the reaction proceeding with high diastereoselectivity for those substrate combinations that result in more than one stereogenic center. Moreover, the opposite relative stereochemistry can be achieved by employing 1,2-disubstituted dienes. A mechanism for the transformation is proposed based upon the relative stereochemistry of the products and studies with isotopically labeled starting materials.

Unified Strategy for 1,5,9- and 1,5,7-Triols via Configuration-Encoded 1,5-Polyol Synthesis: Preparation and Coupling of C15-C25 and C26-C40 Fragments of Tetrafibricin.

Diverse classes of natural products contain chiral 1,5,9- and 1,5,7-triol stereotriads, including the novel fibrinogen receptor antagonist tetrafibricin. Biological activities associated with compounds containing these motifs warrant targeted synthetic strategies to 1,5-polyol families from cheap and easily accessible reagents while avoiding the need to determine configurations at each alcohol stereocenter. In the accompanying paper, we present a solution to these problems via an iterative configuration-encoded strategy that exploits Julia-Kocienski couplings of enantiopure α-silyloxy-γ-sulfononitrile building blocks. The stereocontrol is unambiguous, and the building blocks are available in multigram quantities via asymmetric catalysis. This approach efficiently accessed a C26-C40 subunit of tetrafibricin that contains a syn, syn-1,5,9-triol and all of the stereochemistry and functionality needed to advance toward tetrafibricin. A modification afforded the anti, syn-1,5,7-triol within the C15-C25 fragment of tetrafibricin by merging 1,5-polyol synthesis with diastereoselective intramolecular conjugate addition. The union of the C15-C25 and C26-C40 fragments was achieved via a BF3·OEt2-mediated Mukaiyama aldol construction with high 1,3- anti stereoinduction, revealing some unexpected insights on the impact of silyl protecting groups on 1,3- anti diastereocontrol by a ß-siloxyaldehyde aldol acceptor. Directed 1,3- anti reduction completed the stereostructure of the C15-C40 portion of tetrafibricin, with configurations established by a combination of NMR experiments.